1. Technical Field
Exemplary embodiments of the present invention relate to a semiconductor memory device and, more particularly, to a semiconductor memory device having a resistive element.
2. Related Art
As mobile communication and digital storage technologies rapidly advance, conventional electron charge control-based devices are reaching their performance limits. Thus, different types of memory devices are being developed to overcome performance limits of conventional electron charge devices. For example, next generation memory devices with high capacity, ultra-high speed, and ultra-low power are being developed to satisfy requirements for advanced mobile communication and digital storage devices.
More specifically, resistive memories using a resistive element as a memory medium such as phase-change memory devices are being developed. Phase-change memory devices often use a phase-change material as a resistive medium, where a phase-change material switches between a crystalline state and an amorphous state in response to heat. As the phase-change material, a chalcogenide (GST)-based material which is a compound of germanium (Ge), antimony (Sb) and tellurium (Te) may be used.
A source for providing heat to a phase-change material may be current, where an amount of heat applied to the phase-change material depends on the intensity of the supplied current and the time that the current is supplied. The phase-change material has a resistance that varies according to a crystalline state thereof so that logic information is determined by a resistance difference between different states.
In developing phase-change memory devices, increasing the integration degree and the area of memory devices is useful. However, due to technical limits associates with use of a light source, reduction in a minimum feature size is difficult.